Conventionally, a card reader structured to perform reading of magnetic data recorded on a card and/or recording of magnetic data to a card has been widely utilized. In an industry such as a financial institution where a card reader is utilized, so-called skimming, that is, a criminal attaches a magnetic head to a card insertion part of the card reader and illegally acquires magnetic data of a card, has conventionally become a large issue. Therefore, a card reader has been proposed which includes a metal sensor for detecting that a magnetic head for skimming (hereinafter, referred to as a “skimming magnetic head”) has been attached to a front face side of a card insertion part (see, for example, Japanese Patent Laid-Open No. 2013-37555).
In the card reader described in the above-mentioned Patent Literature, a metal sensor is disposed in an inside of a card insertion part formed in a hollow shape. The metal sensor includes a core formed of magnetic material and a pair of excitation coils and a detection coil which are wound around the core. In the card reader, when a foreign matter including metal material is detected by the metal sensor, a predetermined abnormality processing is executed and reading of magnetic data by the skimming magnetic head attached to a front face side of the card insertion part is capable of being prevented.
A trick of skimming by a criminal has been sophisticated year by year, and a situation has occurred that a device for skimming (hereinafter, referred to as a “skimming device”) such as a skimming magnetic head for reading magnetic data of a card is attached in an inside of the card reader where the skimming device has not attached conventionally. In the card reader described in the above-mentioned Patent Literature, a skimming device which is attached to a front face side of a card insertion part can be detected by the metal sensor, but a skimming device attached to an inside of the card reader cannot be detected by the metal sensor. Therefore, in the card reader, when a skimming device is attached to an inside of the card reader, reading of magnetic data by the skimming device is not prevented.